Leather water repellent



Patented Mar. 16, 1954 LEATHER WATER REPELLEN T ChestemCarlyle Currie, Midland, Mich., assignor toe, Dow Corning Corporation, 'Midland; Micki;

acorpprati'on of. Michigan No DrawingaApplication-August .4,- 1952, Serial No. 302,620,

droxylated aliphatic hydrocarbon zradicalofaless thans-r-liii. carbon {atoms containing less-e than l hygiro yljl eu szr (memo-10 per t y-w ehtof a methylpolysiloxane resin composed of t1i--. methylsiloxane units ands-'SiOzmnits. in, such silicon atoms, is l-ffromr 1,0211. to-;2.5:1; and. (3.) v to 80' er centby weightaofi polysiloxanes having et eneral iormulas otherwisecuredsiand.etoflfinishedlor-unfinishe d leather.

Asa resultn'of impregnationrwitht thescomposi-e.

l p v p ment ,in the compesitionwofl tmps tmsrmvenmn leather Nbtamed those esters having.thegeneral,formnlaJIiiQRM where R is an aliphatic hydrocarbon radical fofa J ingaaaresistance ;to v:wa ter; penetraticn ranging froxn'five fold to ones-hundred fifty fold increase event-hose previouslyknow-n.

Applicatiomof the compositions; to: leathermay w be ;readily; accomplished bywbrushing .or dipping and rmay be-applied'to leathersheets 'or leather articles suehx'as shoesgbeltsyetc. These repellent compositionsemay be'empioyed in the 'form' of solvent-less pastes which may, if desired, con- 2 best "results beingiobtained' witnleath'er 'contaifij-" mg" 10 to' 20- per 'cent of per cent solution is sufficient. i

The methylpolysiloxane resinous"copolyiner, 1

composed of trimethylsiloxaneunits "and i S192 units employed herein; may; be preparediby "the"",f cohydrolysis. of (CI-I3) aSiX'fand Siifiiwh'ere "K ts-r: a hydrolyzable radical, employing, ofc'oursasuch? to' obtain, th'e'-'- dBSilBd'f'? Clix/Si ratio of from 1.011;"tin-2.511; Preferred p ncttionc-zthat z the.-sratio .-of-r methyl radicals to are resinouscopolymers"having a-methylto silr-L proportions as necessary con ratio of from" 1.0:1to;2:5:-1; Alternativel' this copolymermay'be prepared'r'by reacting- (CH3) sSiCl, (CI-IrlaSlQGzHa 01 (CIiQ-QSiOSifCI-I-H '-1 with, an, acidic. silicassol. Sucha methodis mny described the. copendingl applications of W11 liam H. Daudt andLeslieJ. Tyler,...Serial-.N0 184,720, filedr September 13, :l950, and la ssig'nedr to the same assignee .as this..invention.=-. Ihecoal, polymers of trimeth'ylsiloxane and .3102 referred,v

to supra. are .characterizedrby,,being. readily., solu;l blesor dispersable in organic solvents.

The .titanium compounds suitablffonemplOil:, thiseinventiQn-r are lessthan 13.carbon atoms, or a hydroxylated, aliq-l phatic hydrocarbon.- radicalvof lessthan LSTcare, less. -.than(.4 0H,,radi cals, and partially hydrolyzed ,s Ti (ORMJ combon atoms and containing pounds that ,aresubstantially soluble inaliphatic hydrocarbon. solvents. Thus. titaniumesters such' as tetramethyl titanatatetraethyl titanate,.tetra-v-,...--

tain; polishing agents. or inthe form ofsolyent, 4 8Cy1 titanate, octylene,glycolyltitanate, tetraz-ih s lutions;

Preferably (at.least. on; a commercial, 1 scale) ap licat n-is accomp is ed. by; e ployin a s le vent oluticn using;anyv solyentswhichi are harm.-

as stoddardysolvent; naphth'amineral spirits, etc, Excellent results are; obtained "by impregnating leatherto the extentof 1 t'o;;30i'per. cent by weight of the water'repellent composition (based onthe weight of the leather). The impregnation of compositions of this invention is preferred 'with' '55 ethyl hexyl titanate,.-tetradodeeyl titanate tetraaw isopropyl titanate, and any mixtures thereoimam be .used.. Titaniumzesters wherein ,Rf-is the;same. or mixed radicals arelikewisesuitable. .Prefer-;

lessegtogleather. e. g. nonaaromatic. solvents, suchi "45 the groups should have at 3 bon atoms. These esters are preparedrordinarilyi g; by ester interchangeof a titaniumester suchas; tetramethyl titanate with' a higher'boili'rig'alco hol; 1 For "example," octyle'ne" "glycolyltitanate"*is t readily prepared 'byjreacting octyleneglycol with tetramethyl titanate in molar proportion of 4ft0' 1. Partially hydrolyzed Ti (OHM compounds may" be employed if the hydrolysis has notrendered the compounds insoluble in, aliphatic? solvents;

(such as Stoddard 'So'lvent) partially hy' these Water repellent? compositions. As" many applicationsfiofthese? compositions to 'leather'as is necessary "i efiCtT 5 the desireddegree ofimpregnation*mayfbe ems ployed; Ordinarily two applications with a "$15" drolyzed titanium compounds are employed particular care is necessary to prevent undue formation of insoluble TiOz. On the basis of commercial availability, tetrabutyl titanate is preferred. All of the titanium esters mentioned in the exarriples of this application are commercially availab e.

The third essential ingredient employed herein is organopolysiloxanes having the general formula a'.sio T where B may be alkyl or alkylene radicals of less than 4 carbon atoms, or monocyclicaryl radicals, and n has an average value of 2.0 to 2.9 inclusive. These materials are employed in amount of from 15 to 85 per cent by weight of the total composition. Specific examples of operative siloxanes are dimethylpolysiloxane, vinylmethylsiloxane, phenylethylsiloxane, dipropylsiloxane, methylxenylsiloxanes or any mixtures thereof. Also copolymers of such diorganosiloxanes with triorganosiloxanes such as trimethylsiloxane, phenyldimethylsiloxane, etc. are operative. Traces of monoorganosiloxane units may also be present in these siloxanes as long as the value of 11 remains substantially in the range specified.

These organosiloxanes are benzene soluble materials which vary in viscosity from thin fluids to deformable solids. Generally preferred are fluid polymers having viscosities ranging from to 100,000centistokes at 25 C. Methylpolysiloxanes are the preferred species.

The above components may be mixed in the solvent free state by employing common mixing equipment. It is generally more convenient, however, to effect mixing by employing solvents which may be retained after mixing to yield solutions ready for use. Suitable leather polishing waxes and. dyes may be added to the compositions of this invention. Any solvent may be employed which is harmless to leather and capable of dispersing the compositions of this invention.

The outstanding advantages of this invention are clearly demonstrated by impregnating leather and testing in the manner described below.

The leather impregnated in the examples is Tomahawk Kip, a commercial emulsion top vegetable tanned cowhide. However, the products of this invention are equally applicable to leather from horse hide, pig skin, and other animals.

Sample pieces of such leather measuring 4 x 4% inches and varying between 0.05 and 0.06 inch in thickness were tested in an Upper Leather Water Penetration Machine. This machine is a slight modification of the machine pictured and described on pages 401-2 of the August 1947, issue of Journal of the American Leather Chemists Association. This testing machine consists of a pair of V clamping heads, one of such heads being movable downward over an arc of 30. The leather sample is clamped to the V heads to form thereby a leather trough which is sealed at each end by means of gasketed V blocks.

The leather trough so formed is partially immersed in water and flexed by the movable head. Such flexing produces a single wrinkle in the center of the trough and Simultaneously places the upper edges of the leather trough under tension. The machine runs at 72 flexes per minute. The number of cycles required for leather to wet through is determined by observing the appearance of a tiny bead of water which usually appears at either end of the wrinkle. The number of cycles required for the appearance of this drop or water is known as the first drop number.

This invention is illustrated by the following examples but is not limited except as defined in the claims. The benefits of this invention are not obtained employing mixtures whose ingredients are in proportions outside the scope set forth in the claims.

EXAMPLE 1 Samples of leather were impregnated by dipping in Stoddard Solvent (B. P. 308-380 F.) solutions containing the compositions of Table I. Samples were immersed for 30 seconds and then air dried for 16 hours, then reimmersed for 30 seconds and again air dried for 16 hours prior to testing. The amount of impregnation (expressed as per cent pickup) based on the weight of the leather was determined by difference in weight. All impregnated samples were tested in the Upper Leather Penetration Machine and the first drop numbers are recorded in Table I.

Mixtures tabulated in Table I were made by mixing the following materials A, B, and C in various proportions.

A. A methylpolysiloxane copolymer composed of (CI-193810 units and 5102 units having a CI-Ia/Si ratio of 12:1.

B. A methylpolysiloxane having the composition 9'? mol per cent (CH3)2SiO and 3 mol per cent (CH3) 3510 C. Tetrabutyl titanate.

Mixing was readily accomplished by dissolving all components in Stoddard Solvent (B. P. 308- 380 F.) and adjusting the total solids to 15 per cent by weight. Check samples were tested in all cases and the average first drop values tabulated in Table I.

Table I Composition of Mixture in percent by gg g weight p en o Mixture No. pickup flexesbY first (A) (B) (C) eig t drop the water repellency obtained employing binary mixtures AB, BC, and AC. Unimpregnated leather samples have first drop values ranging from EXAMPLE 2 In th same manner as in Example 1, leather samples were impregnated employing a 15 per cent solids solution of mixtures composed of equal weight portions of compositions A, B, and the titanium compounds listed in Table II.

The above titanium compounds are commercially available fluids soluble in Stoddard Solvent or naphtha mineral spirits. They were prepared by reacting a mol of tetramethyl or tetraethyl titanate with 4 mols of 2-ethyl hexanol, 2-ethyl hexanediol 1,3, and isopropanol respectively.

EXAIWPLE 3 When leather is impregnated in the manner of Exampl 1, with a composition consisting of equal parts by weight of compositions A and B of Example 1 and tetramethyl titanate or tetradodecyl titanate, excellent water repellency is obtained.

EXAIMPLE l Mixtures comprising equal parts by weight of compositions A and C and 100 cs. phenylmethylsiloxane or ethylvinylsiloxane fluids, bring about excellent resistance to water penetration when impregnated into leather in accordance with Example 1.

EXAMPLE 5 When a titanium ester such as Ti (OCH2CH2CHZCHZCH2) 4 which may b prepared by ester interchange of tetramethyl titanate with beta-allyl-ethyl alcohol, is employed in place of tetrabutyl titanate in the mixtures of Example 1, equivalent results are obtained.

That which is claimed is:-

1. As a composition of matter, a mixture comprising (1) 15 to 50 per cent by weight of a titanium compound selected from the group consisting of titanium compounds having the general formula Ti(OR)4 and aliphatic hydrocarbon soluble partial hydrolyzates thereof in which compounds R is selected from the group consisting of aliphatic hydrocarbon radicals of less than 13 carbon atoms and hydroxylated aliphatic hydrocarbon radicals of less than 13 carbon atoms and containing less than 4 hydroxy radicals; (2) 5 to 70 per cent by weight of a methyl polysiloxane copolymer composed of trimethylsiloxane units and S102 units, said units being in such proportion that the ratio of methyl radicals to silicon atoms is from 1.0:1 to 25:1; and (3) 15 to 80 per cent by weight of a polysiloxane having the general formula R SiO T where R, is a radical selected from the group consisting of alkyl and alkylene radicals of less than 4 carbon atoms, and monocyclicaryl radicals, and n has an average value of 2 to 2.9, each silicon atom in said polysiloxane (3) having at least one of the defined hydrocarbon radicals attached thereto.

2. The composition of claim 1 where R is an alkyl radical of less than 4 carbon atoms.

3. The composition of claim 1 wherein R is a butyl radical.

4. As an article of manufacture, leather impregnated with l to 50 per cent by'weight based on the weight of the leather of the composition of claim 1.

5. As a composition of matter a mixture comprising (1) 15 to 50 per cent by weight of a titanium compound selected from the group consisting of titanium compounds having the general formula Ti(OR)4 and aliphatic hydrocarbon soluble partial hydrolyzates thereof, in said compounds R being selected from the group consisting of aliphatic hydrocarbon radicals of less than 13 carbon atoms and hydroxylated aliphatic hydrocarbon radicals of less than 13 carbon atoms and containing less than 4 hydroxy radicals; (2) 5 to 70 per cent by weight of a methylpolysiloxane composed of trimethylsiloxane units and SiOa units, said units being in such proportion that the ratio of methyl radicals to silicon atoms is from 1.021 to 25:1; and. (3) 15 to per cent by weight of a polysiloxane having the formula where n has an average value of 2.0 to 2.9, each silicon atom in said polysiloxane (3) having at least one methyl radical attached thereto.

6. The composition of claim 5 where R is butyl.

7. As an article of manufacture, leather im pregnated with 1 to 50 per cent by Weight based on the weight of the leather of the composition of claim 5.

8. As a composition of matter a mixture comprising (1) 15 to 50 per cent by weight of a titanium compound selected from the group consisting of titanium compounds having the general formula Ti(OR)4 and aliphatic hydrocarbon soluble partial hydrolyzates thereof, in said compounds R being selected from the group con sisting of aliphatic hydrocarbon radicals of less than 13 carbon atoms and hydroxylated aliphatic hydrocarbon radicals of less than 13 carbon atoms and containing less than 4 hydroxy groups; (2) 5 to 70 per cent by weight of a methylpolysiloxane copolymer composed of trimethylsiloxane units and SiOz units, said units being in such proportion that the ratio of methyl radicals to silicon atoms is from 1.0:1 to 2.521; and (3) 15 to 80 per cent by weight of a polysiloxane having the formula CHESTER CARLYLE CURRIE.

References Cited in the file of this patent UNITED STATES PATENTS Name Date Gulledge June 20, 1950 Cheronis Sept. 18, 1951 Number 

1. AS A COMPOSITION OF MATTER, A MIXTURE COMPRISING (1) 15 TO 50 PER CENT BY WEIGHT OF A TITANIUM COMPOUND SELECTED FROM THE GROUP CONSSISTING OF TITANIUM COMPOUNDS HAVING THE GENERAL FORMULA TI(OR)4 AND ALIPHATIC HYDROCARBON SOLUBLE PARTIAL HYDROLYZATES THEREOF IN WHICH COMPOUNDS R IS SELECTED FROM THE GROUP CONSISTING OF ALIPHATIC HYDROCARBON RADICALS OF LESS THAN 13 CARBON ATOMS AND HYDROXYLATED ALIPHATIC HYDROCARBON RADICALS OF LESS THAN 13 CARBON ATOMS AND CONTAINING LESS THAN 4 HYDROXY RADICALS; (2) 5 TO 70 PER CENT BY WEIGHT OF A METHYL POLYSILOXANE COPOLYMER COMPOSED OF TRIMETHYLSILOXANE UNITS AND SIO2 UNITS, SAID UNITS BEING IN SUCH PROPORTION THAT THE RATIO OF METHYL RADICALS TO SILICON ATOMS IS FROM 1.0:1 TO 2.5:1; AND (3) 15 TO 80 PER CENT BY WEIGHT OF A POLYSILOXANE HAVING THE GENERAL FORMULA 